The ultimate aim of the proposed research is to enable a substantial improvement in human kidney preservation prior to transplantation by extending the safe storage time and improving outcomes after any given period of storage. This proposal will build upon existing results indicating that a new renal preservation solution developed at 21st Century Medicine (Renasol) is superior to the industry standard, UW solution, in both canine and leporine renal transplant models. The proposal will explore a combination of Renasol and a specific new formulation of protein factors ("trophic factors") that dramatically improve hypothermic storage of dog kidneys. More information will be obtained on the appropriate concentration of trophic factors using the rabbit renal transplant model. A potentially valuable additive for Renasol that may help protect human kidneys from the effects of agonal hypotension will also be evaluated. Canine renal transplants will also be performed using kidneys preserved by simple cold storage for 4 days with Renasol and with Renasol + trophic factors. In anticipation of clinical application, and resulting stability requirements, tests will be conducted, using both the canine and leporine models, to show Renasol retains its effectiveness after months of prior storage at 4 deg. C. These studies will result in a final formulation that will be taken into human clinical trials in Phase II and marketed in Phase Ill. During the course of the proposed studies, urine samples will be collected on a routine basis and subjected to protein profiling using an in-house proteomics workstation. These observations will determine whether the degree of hypothermic injury observed is correlated with definable relative or absolute changes in urinary protein concentrations. This may provide a new predictive diagnostic marker of renal preservation injury. The ability to preserve kidneys with less damage prior to transplantation will significantly reduce the costs and risks of post-transplant dialysis, reduce rejection episodes, and increase the net organ supply.